Author Topic: Treadmill Dyno  (Read 127692 times)

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taylorp035

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Re: Treadmill Dyno
« Reply #210 on: March 22, 2012, 09:36:36 AM »
JW,

The head gasket is not round, but rather the shape  of the entire top surface, which has to seal the cylinder and the valves.  As for the extra head bolt where the intake area once was, no, we did not add another bolt. The rocker parts would kind be in the way and there is not very much material to sink an extra bolt into.  Also, you could loose compression through there.  The valves are straight and are positioned so the engine is a non-interference engine with no head gasket (according to the drawing), but the valves are actually a bit lower, so hopefully the head gasket is thick enough to make up for this.  The compression ratio will be 12.3:1 with a 0.060" head gasket, and 16:1 with no gasket.  More than likely, the connecting rod would break much past 13:1...   The stock engine was supposedly 6:1, which is very, very low and make a poor use of isooctane fuel (I think you can go up past 18:1 with it).

The valves, tappets, springs, and valve seats are from the original engine.  Everything in the block is the same.  The hard part was making sure everything was going to line up and that the head bolts were going to fit.  Simplicity was a high priority.  The really good teams that spend millions of dollars in Europe/Japan have hemispherical engines that are usually ~16:1 C.R. and dual overhead valves and two spark plugs on a 30 cc displacement.  Ours in 148 cc's.

JW

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Re: Treadmill Dyno
« Reply #211 on: March 22, 2012, 04:21:13 PM »
I have been working on a "four cycle steam engine" for years. The engine uses a direct injection valve that uses a briggs valve spring.

Im not sure if your allowed to use direct fuel injection, but I would be willing to donate a license for your team. US 6,928,992  US 7,552,715

http://www.flashsteam.com/L912_Injector.htm

-edit- I would recommend the SO8 not the L912, for direct fuel injection, the SO8 is miniturized version of the L912. I would also be interested in (also donating) development technical support, from machining (your machine shop) to electronic control. This is a direct electromagnetic lift valve not peizo. So you would rely on lift setting for throttling, not pulse width control. but the servo does use pwm -edit-

When im talking with other steam folks, they dont seem to make the connection of compression ratio to volumetric efficiency. For the steam applications 9.5 to 1 is considered high compression when compressing live steam, before injection duration.

I know this is apples and oranges to what your doing with the super milage.
« Last Edit: March 22, 2012, 04:46:39 PM by JW »

taylorp035

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Re: Treadmill Dyno
« Reply #212 on: March 22, 2012, 10:23:03 PM »
We are allowed to us direct injection, but basically, the engine needs to be a 4 cycle combustion engine.... so I guess no steam.  Some people talk about 6 cycle engines too, but I guess that would go against the rules of "4".

Here are the relatively simple rules if you want to see them:
http://students.sae.org/competitions/supermileage/rules/

Quote
When im talking with other steam folks, they dont seem to make the connection of compression ratio to volumetric efficiency.

Is it because there is a larger change in temperature after the power stroke, so the cylinder sleeve is cooler, thus more air can come in the next cycle?   I can see that the higher compression ratio would raise the cycle efficiency....


I sure do seem to find a lot of interesting people on this forum  :D  You never know who you will run into with these creative types of people....

SparWeb

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Re: Treadmill Dyno
« Reply #213 on: March 23, 2012, 08:48:19 PM »
Hi Taylor,
Another thought: Are your pushrods sliding through bare aluminum holes?  If so, a brass sleeve would reduce the friction, and allow tighter tolerances (sliding clearance) so there would be less noise vibration etc.  Getting the right press-fit to keep the brass sleeve in place is a bit of a chore on a "one-off".  Enough suggestions from me that make more work for you!
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

taylorp035

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Re: Treadmill Dyno
« Reply #214 on: March 24, 2012, 04:12:35 PM »
Sparweb,

We now have brass sleeves in there.  The some of the stock engines had no sleeves from the factory, just aluminum valve guides.

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Re: Treadmill Dyno
« Reply #215 on: March 25, 2012, 06:21:54 PM »
Ah just one step behind you!
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

taylorp035

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The Big Reveal
« Reply #216 on: March 31, 2012, 05:31:11 PM »
The day you guys have been waiting for, the new engine now runs and I have pictures of the new car  :) :D ;D






EDIT:   Some more photos of the SAE supermileage car....













« Last Edit: March 31, 2012, 08:28:18 PM by taylorp035 »

electrondady1

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Re: Treadmill Dyno
« Reply #217 on: April 01, 2012, 08:26:00 AM »
it looks fast
after you win the mileage  contest , maybe jack it up a bit, and take it to Utah?
it would look good with salt on it.
 

taylorp035

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Re: Treadmill Dyno
« Reply #218 on: April 01, 2012, 10:49:54 AM »
With the stock engine, the numbers suggest that you could hit about 100 mph on 3 hp :D   But the tires are rated only for about 40 mph....    Previous supermileage cars have been known to go past 50 mph   ;)  From personal experience, much past 35 mph is really scary on 3 wheels and your limited visibility becomes a factor.  Surprisingly, the car is quite stable, so it will usually understeer in a corner instead of rolling over.

As for salt, we loaded our old car with salt after driving it around in the slush around the school.... took all week to clean out of the engine bay and driver's compartment.

ghurd

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Re: Treadmill Dyno
« Reply #219 on: April 01, 2012, 05:54:47 PM »
As for salt...

Oh boy...  Kids these days.
The salt flats?  In Utah?

If you were NOT just messing with E-Daddy, I may have to drive up there and smack you with a perfectly flat salt block!
 :o
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taylorp035

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Re: Treadmill Dyno
« Reply #220 on: April 01, 2012, 07:20:17 PM »
No, I wasn't....  note the original burnout in the dark... the road had an inch or two of slush with salt mixed in it.  The driver had salt all over him when he was done.

electrondady1

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Re: Treadmill Dyno
« Reply #221 on: April 01, 2012, 08:10:11 PM »
this is the place.


they bring  things there to go fast

look familiar?

electrondady1

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Re: Treadmill Dyno
« Reply #222 on: April 01, 2012, 08:15:38 PM »


 taylor i  like your machines shape
it got me thinking, there is probably a scta category for briggs powered streamliners
« Last Edit: April 01, 2012, 08:42:06 PM by electrondady1 »

taylorp035

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Re: Treadmill Dyno
« Reply #223 on: April 02, 2012, 07:34:29 PM »
A rear wheel steering setup can reduce your total frontal area by lowering the area needed for the front wheels.  I would also consider trying out so of the Solar Challenge tires, since they are wider and would have super low rolling resistance and since they are designed for higher speeds.  I bet you could get the drag coefficient down to ~0.08 or so if you tried.  I don't know what the Cd is for my new car or old car, but many other teams come in at 0.12 - 0.15 for the decent teams and  0.075 - 0.1 for the really good teams.  The frontal area for the best cars is less than 0.3 m^2 (extremely small).  My old car was 0.444 m^2 and the one before that was 0.75 m^2.

Of course, driver space is critical when designing these things.... as you will find that many of the top supermileage cars have less than 14" of width for the driver, if not 13" or even 12" where they sit between the front wheels.  A small driver though can fix many of these problems.


Here is our team site with all of our photos that we are now letting the public view.


http://behrend.orgsync.com/org/societyofautomotiveengineers22440/home
« Last Edit: April 02, 2012, 07:47:29 PM by taylorp035 »

taylorp035

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Re: Treadmill Dyno
« Reply #224 on: April 08, 2012, 07:29:52 PM »
We put our new engine on the dyno last friday and even though it only was running at about a 6:1 compression ratio right now (head gasket is blown), we recorded several run north of 15.5% efficient!  Previous runs with the equivalent set up with the L-head were about 13-14% efficient.  Once we get our new spark plug and electronic ignition set up and a new head gasket, I think we can boost the efficiency a few more percent.... hopefully getting to 20+%.  If we could get much past that, I would say we could make a serious run at the North American mpg record  :)  The exhaust note is really cool, kind of like a hit and miss engine and the popping sounds they make.  This week, we will get a new head gasket, hook up the AFR gauge, add the ceramic bearing faceplate, and add the high performance spark plug.

We also made sure our new car is going to fit in the van we plan on taking to competition.... at 118" long, we knew it was going to be a tight fit to get it into a mini van...... to make it fit, we had to move the driver and co-pilots seat up a few notches   8)  The arm rests may end up being removed too on the front seats.

We also had all of the members try and fit inside of the new car.  Turns out that the new car is surprisingly spacious when compared to the last car, as my 6' 1" frame fit side with out cutting my feet off...   Visibility seems good enough to drive @ 15 mph on a 2-3 lane track with a car that is 24" wide  :-\

You can see how little space we have.... the carburetor doesn't even fit pointing towards the tire, so it's going to go towards the firewall.
« Last Edit: April 08, 2012, 07:37:15 PM by taylorp035 »

taylorp035

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Re: Treadmill Dyno
« Reply #225 on: April 17, 2012, 10:57:15 AM »
Things have moving along quickly in the last few days.  The front windows have been cut out and the front wheels mounted.  We were pleasantly surprised by the amount of reward visibility that we have.  The front wheels fit well too, especially considering that we have less than 1/4" of clearance in about 10 spots around the the tires and that everything is hand made :D   We also figured out that you should open the throttle all the way open while doing compression tests.... that way the air can get in the engine  ::)  Definitely felt stupid after figuring that one out.  Now we have 225+ psi of compression!

Next up is thermoforming the front windshield.  Unfortunately, the big machine that our school has to do such things woln't work for our application.  But we do have a 1800 watt heat gun and 3450 W of light bulbs, so maybe we can make something work.  Looks like we need to get it to around 310-350 F and keep it below 370F.


SparWeb

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Re: Treadmill Dyno
« Reply #226 on: April 17, 2012, 12:14:59 PM »
Taylor,
20,000 views!


Quote
Now we have 225+ psi of compression!

Do I read right, comp ratio = 16:1  (or 15:1 if that already includes atmospheric pressure)
Either way, Nice Job.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

taylorp035

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Re: Treadmill Dyno
« Reply #227 on: April 17, 2012, 09:19:13 PM »
20,000 Views 8)

With our 0.060" head gasket, it should be about 12.3:1.  0.040" = ~13.5:1, and 0.000000" = 16:1.  The compression could be higher if the volume calculations were wrong...

Tomorrow we plan on doing some dyno runs and seeing what the best the engine can do.  We also want to test to see how much better the engine is at wider throttle than idle (with a mostly closed valve in carb, which hurts compression).  If there is a huge difference, we can try the fuel injection to eliminate the restriction...

SparWeb

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Re: Treadmill Dyno
« Reply #228 on: April 17, 2012, 09:59:58 PM »
Tomorrow we plan on doing some dyno runs and seeing what the best the engine can do.  We also want to test to see how much better the engine is at wider throttle than idle (with a mostly closed valve in carb, which hurts compression).  If there is a huge difference, we can try the fuel injection to eliminate the restriction...

Here we go with the graphs again!
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

Bruce S

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Re: Treadmill Dyno
« Reply #229 on: April 18, 2012, 07:12:47 AM »
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With our 0.060" head gasket, it should be about 12.3:1.  0.040" = ~13.5:1, and 0.000000" = 16:1.  The compression could be higher if the volume calculations were wrong...
Which head gaskets are you using? there are the standard ones and there used to be available (racing) head gaskets. In my younger days (when full service premium was 0.49/gal) we built them with these ultra-thin tin gaskets , if you have to stay with standard gaskets, grab one the is metal plated.
I will go out on a limb here and say I 'm sure you've already lapped the head and body top to be ubber-smooth?
Nice vehicle!! you're ahead of Chrysler :-) they're now using CF the lighten their Vipers!
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taylorp035

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Re: Treadmill Dyno
« Reply #230 on: April 19, 2012, 11:45:04 AM »
Bruce,

Our head gasket material is has metal in it.  With the 0.040", the gasket makes up about 25% of the total compressed volume.... the chamber is only 9 cc.

I was wrong about the head gasket dimensions from last time...  we are currently running 0.040", which makes it a 12.3:1 ratio.  I was thinking of the numbers for next year's engine ;D   We did lap the valves and the head / block were both face milled at one point.

We were hoping to make the whole body less than 15 lbs, but it came out to 22 lbs due to several mistakes caused by our inexperience.....  it would be nice to have access to a professional shop and use their equipment like some of the other teams do.  With the frame, engine mount, wheel mounts, and windows, we will be at about 35 lbs, which compares to about 52 lbs in the old car or ~100 lbs from 2 years ago.




Visibility is better than ever!  You can also see how nice the shape is   :)    I bet this new car has half the air drag of last year's.  It's also a bit more cozy in terms of space that is left over for components (engine, fire extinguisher, steering, electronics).


Bruce S

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Re: Treadmill Dyno
« Reply #231 on: April 19, 2012, 12:49:01 PM »
I can now see why you kept the design under wraps !!
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taylorp035

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Re: Treadmill Dyno
« Reply #232 on: April 22, 2012, 03:57:32 PM »
Last Friday, we spent a bunch of time trying to thermo-form our front window.  But all we have in terms of tools to heat the plastic (~24" x 36") is a hair dryer style heat gun (1550 W).  So we made ourselves our own oven with cardboard and high temp duct tape.  As for insulation, we used a combination of a large amount of cardboard and pink foam, but we found out that the foam melts at 240 F, well below the ~350F we needed to reach.  After 4 hours, we finally made enough improvements to our cardboard oven enough to hit 332 F with the heat gun and a 1800 W hair dryer.  Unfortunately, you need to keep the plastic above 320 F for it to be flexible and below 370F to prevent bubbles.  By the time we tore apart our oven and applied the plastic to the mould, it had cooled off too much.  We got the main curve in the window, but the 2nd axis curve (the side profile curve) did not happen.  We have a 2nd piece of plastic if we want to try again, but we may not have enough time to do so.

We also broke our steering in the front, so that needs to be fixed.  But on the plus side, we found a solution to our battery management issues to pass the rules.  We also ordered a new set of points for the engine, since we have vaporized the old ones in ~50-100 h of running it.  This was affecting our efficiency majorly.

JW

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Re: Treadmill Dyno
« Reply #233 on: April 22, 2012, 04:15:49 PM »
If you used some small gauge sheet metal instead of cardboard for the oven, then line it with fiberglass house insulation with another layer of sheet metal(with a door), you could get to your work piece out quicker using that door (without tearing apart a cardboard box) ,then the adjacent area you could use some 5/8 thick foam board and make a sauna room adjacent to the oven,(with a door also) steam it up pretty good and fashion your work piece on the mold in there.

Dry air around where your working is going to cool too quickly, and without some form of humitity control for the work area, when you fashon it to the mold it will be too cool. the mold should already be as hot as the sauna room. then when youve got it clamped down to the mold take it out of there to set.

JW

taylorp035

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Re: Treadmill Dyno
« Reply #234 on: April 22, 2012, 05:14:09 PM »
We have aluminum sheet metal, but no fiberglass insulation.  Our only insulation sources were layers of cardboard with some air pockets and the pink foam.  If we try it again, we will probably use some wood as the side walls and the support structure.   

Our cardboard over was hinged on the top so you could just open it up, but we had accidentally taped it shut while adding the various pieces of insulation.

Also, we had to make sure the edges of the plastic were not hot so we could grab it since we only had 5 gloves (and there were welding gloves, so it wasn't ideal).

You can check out the photos of it in here under the Build Photos (3):

http://behrend.orgsync.com/org/societyofautomotiveengineers22440/Pictures

JW

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Re: Treadmill Dyno
« Reply #235 on: April 22, 2012, 05:21:07 PM »
Well in that case, I would submerge it into a pool big enough for it, and use heat transfer fluid with the temp you specify.

I guess your right its not really a good conductor of heat (the work piece) so you should have what you need.

Hope it goes well, you've solved simular problems in your posts here related to the project.


JW

taylorp035

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Re: Treadmill Dyno
« Reply #236 on: April 22, 2012, 05:27:34 PM »
A big deep fryer would do the trick   :D    Now where to find a deep fryer that we can use.....

JW

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Re: Treadmill Dyno
« Reply #237 on: April 22, 2012, 05:45:47 PM »
If you had a metal pan that would hold it(insulated outside), you could get 500f  heat transfer fluild http://www.radcoind.com/Profile.html

You would need a pump like this  http://www.marchpump.com/809-br-brushtype  I have one of these and have heated the transfer fluid to about 345f sustained.

The pump runs on 12 volt, and I would use a coil heat exchanger on the output to the tank.


taylorp035

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Re: Treadmill Dyno
« Reply #238 on: May 03, 2012, 07:18:55 PM »
YAY!!!!!!!!!   Finals are done for, so tomorrow will be ~17 hours of non-stop supermileage time   :D

Earlier this week, we finished sanding the body (a good 15 man hours) which was extended another 2 hours since we got oil on the top of the car (shown below).  One of the bolts that was on our side plate cover (about a 1/2" diameter) wiggled loose and oil sprayed out of the engine while it was running....  the oil covered my laptop, a desktop computer, my brother's hand and the top of the car that was on the ground near by (which I had just finished sanding 2 minutes earlier).  Since you don't really want to paint over top of an oily surface, I tried to wash it off, but it had stained the lid real bad.  So another 2 hours of sanding was done with a DA sander.  But at least the top is extra light weight now....



We then weighed the car with the windows, top, frame, roll hoop and the body.... coming in at an impressive 31.2 lbs.  That makes it about ~6-7 lbs / m^2 of surface area.



Next up was installing the engine with the reinforced engine mount (hoping to skip the turn buckle this year).  We also finished version 2.0 of the rear wheel mounts, with our radical carbon fiber lead springs.  They are about as stiff as a plastic fork, but they should hold the axle just fine and allow for an adjustment of ~1/2" forwards and back.  The rest will be tied down with an array of titanium and some turnbuckles.  The downside to this is that there is almost no room to get your arms in the back to assemble it... definitely a "no wrist watch" zone  :-\   Before sanding the car, it is kind of like sticking your arm into the sharp needles of a pine tree....



As for space around the engine, I'll let the pictures do the talking.... note the missing carburetor (it doesn't fit right now...) and how close the flywheel is.





There are many more places where the clearance is less than ~1/8", especially around all 3 tires.



taylorp035

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Re: Treadmill Dyno
« Reply #239 on: May 08, 2012, 12:11:40 PM »
A fun photo from my CFD work on the car.  This new software that I have could work really well with designing and simulating a wind turbine.... assuming there was enough time to do so.  Autodesk Simulation CFD.

The large version link:
http://i47.tinypic.com/avg56q.png


640x480 version: